 COMPOSTING TOILETSWritten by CAT's free information serviceemail: info@cat.org.uk; tel: 0845 3308373 or 01654 705989 Click here to download a printable version of this sheet (2 sides A4, PDF format, 50KB). Introduction Most of us are connected to a mains sewage system - usually a very convenient and trouble free way of getting rid of our waste. However perhaps you want to reclaim some of the valuable nutrients you flush away, or save on water, or don't have access to the main sewage system, and here an independent sewage treatment system may be the answer. For details of wet sewage treatment systems, see our Small-scale Sewage Treatment Systems information sheet. Another option is a composting (or dry) toilet. These don't use any water and compost the waste so that you can use it on the garden. Most types, commercial or DIY, need a fair bit of room to allow composting to occur at a steady pace, as it is best left for up to two years to decompose thoroughly. Addition of the right amount of 'soak' gives good decomposition. A 'soak' is a source of carbon, and typical materials include sawdust, straw or earth. Keeping urine separate is usually the key to a successful composting toilet, otherwise they can become anaerobic and smelly. As urine is high in nitrogen, potassium and phosphorus, if collected separately it can be used as a fertiliser (on non-food plants) when mixed about 1:10 in water. Another simple option is a 'straw bale urinal'. This consists of a bale of straw (ends uppermost), for men to urinate on. The liquid soaks in and composts the middle of the bale in a few months. Technicalapproaches include flat panels in the front of compost toilets to capture and divert urine. Bucket toilets are the cheapest and most basic kind of dry toilet. The waste needs to be emptied into a suitable container for composting. There are now more 'civilised' versions of these, and as they are fairly compact and portable they can be put in almost any location. If you can keep the urine separate, then in an average house these toilets might only need emptying once every few months. De-watering toilets are more expensive, and use fans or electric elements to dry the waste. They use lots of energy and don't compost the waste, so generally we do not recommend them. To avoid having to handle raw sewage, you can buy or build a dual-chamber compost toilet. Each chamber is sized to fill up over a year. The seat can be switched between chambers, so that the second is filled whilst the first composts down completely. The soil produced is more pleasant to remove, and can be put straight on the garden, though we recommend its use on non-food plants. You can spend anything from a few hundred to several thousand pounds on a dry or composting toilet; those at the lower end of this scale require a more 'hands-on' attitude to maintenance. If you are off mains sewerage and install a composting toilet, bear in mind that you will still need to deal with grey water. This may just involve a simple soak-away pit, or diversion for garden irrigation. Other approaches will be similar to those mentioned in our Small-scale Sewage Treatment Systems Information Sheet, perhaps a small septic tank & leachfield system, or a vertical flow reed bed. Our Making Use of Grey Water in the Garden tipsheet (50p through our pay-per-view page) looks at many simple ways to divert grey water directly into your garden, using basic traps to catch grease and solids. The use of 'eco' washing and cleaning products is not only recommended if you arediverting grey water onto your garden, it is also good practice for reducing pollution in general. Get in touch to ask us about suppliers of diverters and eco-friendly cleaning products. For those put off by the front end of compost toilets, a device called an Aquatron (about £500) can be fitted to the outlet of a flush toilet, to separate the solids and liquids. The former drop into a composting chamber; the latter are treated, for example, in a leachfield or reed bed. If you are interested in installing some kind of composting toilet, then get hold of our book Lifting the Lid - an ecological approach to toilet systems, by Louise Halestrap and Peter Harper. It considers the environmental problems associated with current sewage treatment, and the alternatives, including low-flush and dry or composting toilets; designs for DIY composting toilets; and what to do with urine and grey water. It contains case studies detailing the advantages and disadvantages of commercially available alternative toilet systems, written by their users. A variant on the compost toilet is the 'treebog'. These are simpler; usually a basic cubicle over a compost heap with lots of fast-growing willow planted around it. They are an effective option as temporary toilets for outdoor events & festivals, but can also be built for more permanent use. A wire mesh barrier filled with straw keeps rodents out of the heap and keeps the compost aerated. CAT COURSES, CONSULTANCY AND MAIL ORDER The publications listed are all available to order from our Online Shop. CAT Tipsheets are also available to download as pdf files from the pay-per-view section of our website. CAT runs residential courses in sewage systems, domestic or large scale, including compost toilets, reed bed design, off-mains water supplies, etc. See the short courses section of our website for further details. CAT Consultancy offers professional advice on all sanitation systems. Visit the CAT Consultancy page for information. FURTHER INFORMATION AND CONTACTS: Natsol Ltd Solution Elements For information on treebogs, see the Steward Community Woodland website: www.stewardwood.org or contact Biologic Design on 01886 884721. Please note: mention of a company does not necessarily constitute a recommendation. Potential customers are advised to contact several companies to compare products, services and prices. You can also contact us with any further questions.
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